Why build a clock that displays four letter words? The current time is everywhere; on your PC, smartphone, GPS, MP3 player, etc. Heck, you may even own a watch! Four letter words are pretty common as well.

So why then?
1st) I had this display that I bought from DealExtreme.Com. The only reason I got it was because it was so cheap.

2nd) I wanted to experiment with writing/reading data from an EEPROM with a microcontroller.

3rd) I wanted to experiment with controlling two devices on the I2C bus in one application.

But…. I wanted a fun project idea to make the effort seem somewhat worthwhile and settled on a Four Letter Word Clock.

If you you just want to see the results and are not interested in the build details, here is a short video demo.

The time is shown in 24 hour format on the left four 7-segments. Every second a different four letter word is shown on the right four 7-segments. The eight LEDs under the 7-segments progress from left to right as a way to display seconds. If you listen closely to the video and you can hear a relay that gives the clock a mechanical ticking sound.

The buttons under the LEDs are used to set hours (S1), minutes (S2), increase display brightness (S6), decrease display brightness (S7), and turn ON/OFF the mechanical ticking sound (S8) from the relay.

The major components of the build are (full schematic to follow):
- Eight x 7-Segment + 8 x Red/Green LED + 8 x Input Button Display Module
- 24LC256 EEPROM to store the 1,003 four letter words
- DS1307 Real Time Clock (RTC) for time keeping
- Small relay to provide a clock like, mechanical ticking sound
- PICAXE 18M2 microcontroller with custom code provides the brains”

Link

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